Police who obtained a murder suspect's DNA by tricking him into licking an envelope didn't violate any privacy laws, even though the letter was from a fake law firm, the [Washington] state Supreme Court ruled Thursday.

In a 6-3 ruling, the court held there is no state or federal privacy interest in the spit used to seal a person's mail.

Licking an envelope, the majority wrote, is “analogous to a person spitting on the sidewalk or leaving a cigarette butt in an ashtray.”

It also didn't matter that Seattle detectives got the DNA sample by posing as lawyers preparing a class-action lawsuit.

Even though pretending to be a lawyer is illegal under state law, police didn't violate the suspect's rights and didn't gather any privileged or confidential information, the court held.

The result is partly explained by the grisly facts:

The decision upholds the second-degree murder conviction of John Athan, a Palisades Park, N.J., man found to have killed a 13-year-old girl in Seattle in 1982, when he was 14.

The girl's murder went unsolved for years, until cold-case detectives fooled Athan into licking the envelope and sending it back to police.

Even so, the court seems to have given up a number of hostages to fortune:

In Thursday's ruling, the court's majority said collecting Athan's saliva from the envelope did not raise the same privacy concerns as would forced collections of blood or urine.

“There is no subjective expectation of privacy in discarded genetic material just as there is no subjective expectation of privacy in fingerprints or footprints left in a public place,” the court ruled.

Athan also wasn't protected by attorney-client privilege in the case because the saliva used to seal the envelope is not an actual “communication,” the court said.

Although Athan believed he was sending the letter to a lawyer, detectives were allowed to open the mail because their names were listed – albeit as fake attorneys – on the original letter, the court ruled.